QuestionMay 4, 2026

Which expression is a factor of 4x^2-25x-21 7 x-3 x-7 x-2 x-6

Which expression is a factor of 4x^2-25x-21 7 x-3 x-7 x-2 x-6
Which expression is a factor of 4x^2-25x-21 7
x-3
x-7
x-2
x-6

Solution
3.7(144 votes)

Answer

x - 7 Explanation 1. Factorize the quadratic Use **ax^2+bx+c factoring**: 4x^2 - 25x - 21. Multiply a \cdot c = 4 \cdot (-21) = -84. Find two numbers that multiply to -84 and add to -25: -28 and 3. 2. Split the middle term 4x^2 - 28x + 3x - 21. 3. Group and factor 4x(x - 7) + 3(x - 7). 4. Identify factors (4x + 3)(x - 7), so x - 7 is a factor.

Explanation

1. Factorize the quadratic <br /> Use **$ax^2+bx+c$ factoring**: $4x^2 - 25x - 21$. Multiply $a \cdot c = 4 \cdot (-21) = -84$. Find two numbers that multiply to $-84$ and add to $-25$: $-28$ and $3$. <br />2. Split the middle term <br /> $4x^2 - 28x + 3x - 21$. <br />3. Group and factor <br /> $4x(x - 7) + 3(x - 7)$. <br />4. Identify factors <br /> $(4x + 3)(x - 7)$, so $x - 7$ is a factor.
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